There has been widely known a horizontal bag-making/packing/packaging machine in which, while packaging articles are successively fed into a packaging material such as, for example, a film and the like being fed out horizontally in the form of a tube through means of a bag-making device, the longitudinal end portions of the tubular packaging material containing the packaging articles are subjected to lengthwise sealing upon the overlapping faces thereof, followed by crosswise sealing and cutting of the tubular packaging material upon both ends of each packaging article so as to successively produce oblong pillow type packages. In this connection, the above longitudinal sealing is generally referred to as "center sealing"; whereas the crosswise sealing, "end sealing", and these latter mentioned terms will be used hereinafter, respectively.
The horizontal bag-making/packing/packaging machine mentioned above has various types of working mechanisms such as, for example, a conveyor for feeding packaging articles, feed rolls for delivering a packaging material, rolls for achieving center sealing, sealers for achieving end-sealing for the packaging material and others. The driving system in the conventional packaging machine described above has one main motor serving as a common driving source and is designed to drive a plurality of working mechanisms mentioned above in connection with one another through means of mechanical power transmission systems, respectively, using this motor.
As described above, when the tubular packaging material containing packaging articles is end-sealed on both sides of each packaging article, it is necessary that the packaging articles be disposed at regular positions relative to the timing of the sealing operation to be effected by means of the end-sealing mechanism. Generally, the packaging articles are fed by means of the conveyor disposed upstream into the tubular packaging material to be fed out downstream, unit by unit, at a predetermined feeding time in synchronization with the sealing time of the end-sealing mechanism. Accordingly, the packaging articles are arranged within the tubular packaging material at regular positions relative to the sealing time operation.
Therefore, within a horizontal bag-making/packing/packaging machine, it frequently happens that the packaging articles contained within the tubular packaging material deviate from their regular positions relative to the sealing time operation due to various factors such as, for example, vibration generated during the operation of the packaging machine, conditions effected by means of the shape of the packaging article, differences between the coefficient of friction of the packaging article and that of the tubular packaging material, errors in the timing of the feeding the packaging article, and the like. Thus, if the packaging article should deviate from the regular position within the tubular packaging material, the sealers provided within the end-sealing mechanism are interfered with through means of contact with the packaging article when the packaging article is passed through the end-sealing mechanism to effect the end-sealing and cutting operations, resulting in defective articles within the packages obtained.
Accordingly, within a conventional packaging machine having a purely mechanical operational system, such as, for example, as shown in Japanese Patent Publication No. 160209/1983, there is employed a system wherein a clutch and a clutch brake are attached, respectively, to a pair of endsealer shafts disposed in a vertical relationship, so that the clutch may be disengaged when a detector detects a deviation of a packaging article, whereby the brake is actuated so as to stop the end sealers.
However, the packaging machine having the abovementioned construction involves problems wherein substantial mechanical shock is produced when the end-sealing mechanism is stopped or started as a result of the clutch on/off operation, the response time to the detection of the deviation so as to stop the sealers is slow, and the like. For such reasons, within the conventional packaging machine, the above construction was not applicable unless the machine is operated at a low rate of speed of approximately 20 rpm.